U.S. Pat. No. 5,175,038 relates to a highly bulked continuous filament yarns, comprised of filaments having a denier per filament of 10-25 and a trilobal filament cross section of modification ratio 1.4-4.0, including filament nylon yarns that have a yarn bulk level of at least 35, which can be ply-twisted together to high-twist levels and can be used in carpets at high-twist levels.
U.S. Pat. No. 3,962,159 discloses graft copolymers prepared by condensing a polyamideamine substrate with starch and a condensing reagent.